Non-Intrusive Cable Fault Diagnosis Based on Inductive Directional Coupling

This paper develops and applies an inductive directional coupling technology based on spread spectrum time domain reflectometry for non-intrusive power cable fault diagnosis. Different from existing capacitive coupling approaches with large signal attenuation, an inductive coupling approach with a capacitive trapper is proposed to reduce signal attenuation, restrict transmitting the detection signal to power source, and eliminate the effect of the power source impedance mismatch. Moreover, a novel structure with two parallel couplers is developed to enhance the effect of capacitive trapper with small capacitance. The development, design, analysis, and implementation of the proposed approach are discussed in details. A series of simulations and experiments on cables with different fault modes at different locations are conducted, along with comparison with existing capacitive coupling approaches, to verify and demonstrate the effectiveness of the proposed method.

I. Introduction

Despite the rapid development of power transmission technology, wired networks remains a fundamental pillar for the power transmission and signal transmission in aerospace, automotive, telecommunications, and energy distribution. Stress factors, including water, ultraviolet ray, temperature, vibration, overload, and aging [1], will cause degradation of cable conditions and eventually lead to failures, such as open circuits, short circuits, and intermittent faults. These faults, if not properly handled, may lead to onboard fires, system damage, power interruptions, or other catastrophic incidents. Therefore, the research on on-line detection and positioning of cable faults is important as it monitors the health of the cable in real time to improve the reliability of the power and signal transmission on cables [2].